[HerrineKim] Week 7

number-of-islands/HerrineKim.js

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+// 시간 복잡도: O(m * n)
+// 공간 복잡도: O(m * n)
+
+/**
+ * @param {character[][]} grid
+ * @return {number}
+ */
+var numIslands = function (grid) {
+  if (!grid || grid.length === 0) return 0;
+
+  const rows = grid.length;
+  const cols = grid[0].length;
+  let islandCount = 0;
+
+  const dfs = (row, col) => {
+    if (row < 0 || row >= rows || col < 0 || col >= cols || grid[row][col] === '0') {
+      return;
+    }
+
+    grid[row][col] = '0';
+
+    dfs(row - 1, col);
+    dfs(row + 1, col);
+    dfs(row, col - 1);
+    dfs(row, col + 1);
+  };
+
+  for (let i = 0; i < rows; i++) {
+    for (let j = 0; j < cols; j++) {
+      if (grid[i][j] === '1') {
+        islandCount++;
+        dfs(i, j);
+      }
+    }
+  }
+
+  return islandCount;
+};

set-matrix-zeroes/HerrineKim.js

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+// 시간 복잡도: O(m * n)
+// 공간 복잡도: O(m + n)
+
+/**
+ * @param {number[][]} matrix
+ * @return {void} Do not return anything, modify matrix in-place instead.
+ */
+var setZeroes = function (matrix) {
+  if (!matrix || matrix.length === 0) return [];
+
+  const rows = matrix.length;
+  const cols = matrix[0].length;
+
+  const zeroRows = new Array(rows).fill(false);
+  const zeroCols = new Array(cols).fill(false);
+
+  for (let row = 0; row < rows; row++) {
+    for (let col = 0; col < cols; col++) {
+      if (matrix[row][col] === 0) {
+        zeroRows[row] = true;
+        zeroCols[col] = true;
+      }
+    }
+  }
+
+  for (let row = 0; row < rows; row++) {
+    for (let col = 0; col < cols; col++) {
+      if (zeroRows[row] || zeroCols[col]) {
+        matrix[row][col] = 0;
+      }
+    }
+  }
+
+  return matrix;
+};